Syntheses and properties of a unsymmetrical photochromic diarylethene with a trifluoromethyl group

A novel unsymmetrical diarylethene derivative bearing both thiazole and thiophene moieties, in which a trifluoromethyl group was substituted at the meta-positions of the terminal phenyl ring, was synthesized. At the same time, its photochromic properties and fluorescence switch were investigated in detail. The results showed that this compound exhibited reversible photochromism, undergoing reversible cyclization and cycloreversion reactions upon alternating irradiation with UV and visible light both in solution and in PMMA film, and its absorption maxima were observed at 610 nm in hexane and at 495 nm in PMMA amorphous film, respectively, upon irradiation with 297 nm UV light. The fluorescence intensity of diarylethene decreased dramatically along with the photochromism from open-ring isomer to closed-ring isomer upon irradiation with 297 nm UV light in PMMA. In hexane solution, the open-ring isomer of the diarylethene 1 exhibited relatively strong fluorescence at 430 nm when excited at 300 nm.